[PATCH v15 15/23] KVM: selftests: Call KVM_TDX_INIT_VCPU when creating a new TDX vcpu

[Lisa Wang <wyihan@google.com>]

From: Sagi Shahar <sagis@google.com>

TDX VMs need to issue the KVM_TDX_INIT_VCPU ioctl for each vcpu after
vcpu creation.

KVM_TDX_INIT_VCPU has a strict prerequisite for the CPUID state. To
satisfy this requirement, call KVM_TDX_GET_CPUID and KVM_SET_CPUID2 to
pull the CPUID configuration from the TDCS and commit it into KVM,
allowing KVM_TDX_INIT_VCPU to succeed.

Additionally, unlike tdx_vm_ioctl(), tdx_vcpu_ioctl() doesn't check
hw_error. KVM's vCPU-scoped TDX ioctl handlers don't propagate SEAMCALL
errors into hw_error: the error is handled in the kernel and only an
errno is returned. Checking the ioctl's return value and errno is
therefore sufficient.

Signed-off-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Lisa Wang <wyihan@google.com>
---
 .../selftests/kvm/include/x86/tdx/tdx_util.h       | 20 +++++++++
 tools/testing/selftests/kvm/lib/x86/processor.c    | 48 ++++++++++++++++++----
 2 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
index e529c587aeae..f5b2f32f2118 100644
--- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
@@ -46,6 +46,26 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)
 		    (unsigned long long)hw_error);			\
 })
 
+#define __tdx_vcpu_ioctl(vcpu, cmd, _flags, arg)			\
+({									\
+	union {								\
+		struct kvm_tdx_cmd c;					\
+		unsigned long raw;					\
+	} tdx_cmd = { .c = {						\
+		.id = (cmd),						\
+		.flags = (u32)(_flags),					\
+		.data = (u64)(arg),					\
+	} };								\
+									\
+	__vcpu_ioctl(vcpu, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd.raw);	\
+})
+
+#define tdx_vcpu_ioctl(vcpu, cmd, flags, arg)				\
+({									\
+	int ret = __tdx_vcpu_ioctl(vcpu, cmd, flags, arg);		\
+	TEST_ASSERT(!ret, "%s failed, errno: %d (%s)",			\
+		     #cmd, errno, strerror(errno));			\
+})
 void tdx_init_vm(struct kvm_vm *vm);
 void tdx_vm_setup_boot_code_region(struct kvm_vm *vm);
 void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 nr_runnable_vcpus);
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 4a753fb43007..4af9cbf3fabb 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -876,16 +876,48 @@ gva_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
 		    "__vm_alloc() did not provide a page-aligned address");
 	stack_gva -= 8;
 
+	return stack_gva;
+}
+
+static void tdx_vcpu_init(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid2 *cpuid;
+
+	cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
+	tdx_vcpu_ioctl(vcpu, KVM_TDX_GET_CPUID, 0, cpuid);
+	vcpu_init_cpuid(vcpu, cpuid);
+	free(cpuid);
+	tdx_vcpu_ioctl(vcpu, KVM_TDX_INIT_VCPU, 0, NULL);
+}
+
+struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, u32 vcpu_id)
+{
+	struct kvm_mp_state mp_state;
+	struct kvm_vcpu *vcpu;
+	struct kvm_regs regs;
+
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
-	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
-	vcpu_init_sregs(vm, vcpu);
-	vcpu_init_xcrs(vm, vcpu);
 
-	/* Setup guest general purpose registers */
-	vcpu_regs_get(vcpu, &regs);
-	regs.rflags = regs.rflags | 0x2;
-	regs.rsp = kvm_allocate_vcpu_stack(vm);
-	vcpu_regs_set(vcpu, &regs);
+	/*
+	 * Both kvm_get_supported_cpuid() (for legacy VMs) and KVM_TDX_GET_CPUID
+	 * (for TDX VMs) return VM-scoped CPUID. e.g. the APIC ID isn't
+	 * populated per vCPU. This is fine because KVM selftests don't
+	 * currently test CPUID topology enumeration.
+	 */
+	if (is_tdx_vm(vm)) {
+		tdx_vcpu_init(vm, vcpu);
+	} else {
+		vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
+
+		vcpu_init_sregs(vm, vcpu);
+		vcpu_init_xcrs(vm, vcpu);
+
+		/* Setup guest general purpose registers */
+		vcpu_regs_get(vcpu, &regs);
+		regs.rflags = regs.rflags | 0x2;
+		regs.rsp = kvm_allocate_vcpu_stack(vm);
+		vcpu_regs_set(vcpu, &regs);
+	}
 
 	/* Setup the MP state */
 	mp_state.mp_state = 0;

-- 
2.56.0.rc1.315.gc6ed9934b7-goog